Collapsible tap for pipe couplings



A ril 26, 1938. w. J. HOGG OOLLAPSIBLE TAP FDR PIPE COUPLINGS Sheets-Sheet 1 Filed Dec. 6, 1934 INYENTOR April 26, 1938. w J HOGG 2,115,365

COLLAPSIBLE TAP FOR PIPE COUPLINGS Filed Dec. 6, 1954 5 Sheets-Sheet? l INVENTOR i JHO 5 Sheets-Sheet 5 W. J; HOGG GOLLAPSIBLE TAP FQR PIPE COUPLINGS April 26, 1938.

I Filed Dec. 6, 1934 April 26, 1938. w, J HOGG I 2,115,365

COLLAPSIBLE TAP FOR PIPE COUPLINGS Filed Dec. 6, 1934 5 Sheets-Sheet 4 6 20 2.5 5 l -1.3 1t 15 ATTORN a April 26, 1938.

w. J. VHOGG 2,115,365

COLLAPSIBLE TAP FOR PIPE COUPLINGS 5 sheets-sheet 5 Filed Dec. 6, 1934 INVENTOR fizazaznfh o g BY 'YATTRNEYI Patented Apr. 26, 1938 entree STATES PATENT OFFICE COLLAPSIBLE TAP FOR PIPE COUPLINGS William J. HOgg, Cleveland, Ohio, assignor to The National Acme Company, Cleveland. Ohio,

a corporation of Ohio This invention relates to collapsible taps, the object of the invention being to provide an improved collapsible tap having circular chasers or cutters shiftable radially of the tap body and which, in the form shown, are automatically shiftable during the cutting of the pipe thread thereby to provide a receding tap effective to cut a tapered thread interiorly of the pipe or coupling, and which circular cutters are automatically collapsed when the thread has been cut, and adjustable for various diameters of pipe threads within the range of the tap.

A further object of the invention is the provision of an improved tap comparatively simple in construction and efficient in operation and in which the body of the tap may be utilized with interchangeable heads for threading different sizes or diameters of pipesor couplings, or carrying four, five or six and up to twelve circular chasers so that, inthreading large sizes of pipe couplings, a large number of chasers may be used, thus distributing the depth of the cuts and obtaining a better and more accurate thread and also prolonging the life of the chasers by reducing the amount of grinding necessary of the chasers. v

A still further object of the invention is the provision of a circular chaser collapsible receding tap having means. for resetting the tap for starting the threading; means for adjusting the chasers or cutters to out different diameters of threads within the range or limits of the tap; adjustable means for controlling the length of the thread to be cut; means for automatically collapsing the cutters when the'thread has been cut, and means for cutting a tapered thread on the pipe or coupling, and which tap also embodies means whereby various sizes and numbers of cutters or chasers may be interchangeably used with the same tap body.

A further object of the invention is the provision of a circular chaser collapsible tap having a floating adapter or floating drive whereby the tap may be properly aligned in the event the coupling to be threaded does not line up perfectly with the driving spindle rotating the tap.

In the drawings accompanying and forming a part of this specification, Fig. l is a longitudinal section of this improved tap;

Fig. 2 is also a longitudinal section thereof at right angles to that shown in Fig. 1;

Fig. 3 is a cross sectional View taken on the line 3-3 of Fig. 1; r I

Fig. 4 is a cross sectional View taken on the line 4-4 of Fig. 1;

Fig. 5 is a cross sectional view taken on the line 55 of Fig. 1, illustrating a front view of the tap within the pipe coupling and with several of the circular chasers removed;

Fig. 6 is a front view of a chaser holding block with the chaser shown in dotted lines;

Fig. '7 is a transverse sectional view of Fig. 6;

Fig. 8 is a detail sectional View of the block and serrated bushing for positioning the chaser on the block;

Fig. 9 is also a sectional View of the chaser mounted in its block, and

Figs. 10 to 13 are partly sectional views of chasers and their blocks and illustrating the angular position or setting of the chasers With relation to each other.

Similar characters of reference indicate the corresponding parts in the several views.

Before explaining in detail the present improvement and the mode of operation thereof, I desire to have it understood that the invention is not limited to the details of construction and arrangement of parts illustrated in the accompanying drawings since the invention is capable-of other embodiments, and that the phraseology which I employ is for the purpose of description and not of limitation.

The tap is rotated from the rotating spindle of and is fed forward in the way usual in standard machines of this type and in the present instance, is connected with the rotating spindle of the machine by a floating adapter hereinafter described. Of course, the work may be rotated relative to the tap and it will be understood that the forward travel of the tap is controlled by a lead screw similar to that on any standard threading machine.

The tap may also be used for cutting straight threads instead of tapered threads, in'which case, of course, the core piece would not be tapered in the manner hereinafter described.

This improved tap, in the preferred form thereof, comprises a body I having an axial bore in which is located a core or core piece 2. This body I and core 2 have a relative longitudinal movement when assembled to cut tapered threads and also have a relative rotary movement for adjusting the cutters to out various diameters of work.

At the front end of the body is located a detachable and interchangeable head or nose 3 secured to the body I by suitable bolts or screws and dowel bushings 4 whereby one head carrying a set of circular chasers may be removed and another head carrying a different number of chasers or different sizes of chasers substituted.

as the occasion may require so that it is only necessary to change'the heads and blocks to 'take care of different sizes of couplings beyond the limits of adjustment of the chasers of each head.

These various heads may be used with the same tap body, thus materially reducing the investment of'the customer as well as the. cost of producing the taps.

The detachable face thereof with a series of radially located guide ways or recesses! for the reception of radially sliding chaser blocks 6 (see Figs. 6} 7 and :8), six thereof being shown in Fig. 5... Each of these recesses is T-shaped for the reception or a onepiece, stepped, correspondingly-shaped chaser block 6 to which the chasers' are suitably secured. 7 Each of the'chaser blocks 6 is provided with a pair of laterally extending pins 1 projecti-ng' into circularly formed slots'8 in the head andin these slots are located springs 9 held in place by screw.

7 plugs ID andin position-to'engagethe pinsof the T blocks to hold the blocks'in engagement with the core piece 2 {and also to "shift the chaser blocks and thereby the 'ch'asers inwardly-to collapse the of thetap but straight in the direction of the' depth of the tap for cQ-opie'ration withsuitable cam-formed surfaces'28 of the core 2 whereby, on the rotary adjustment of the core in the manner hereinafter described, the chaser blocks and .thereby the chasers are adjusted to make t-h'e Y proper size of cut. Inl the rear-of this land surface, the blocksare provided with 'a'n'inc'lined or cam surface=l3 adapted to cO-op'erate with the angularend .4 4 of the core rii whereby, at the proper time, the chasers may be released from the work' through the medium ofthe spring actuated means hereinbefore described;

The front face of each"supporting blockis inclined transversely thereto as '6 see Fig-E9, where by the chasers willbeang'ularly set or inclined to the 'front face of the tap body, see-Figs, 1 and 9, so that, while the grooves I '4 of the chasers are cut circularly'straightand 'notfispirally, they yet 7 have the effect ofspirallycut grooves. Thefront faces of 'tl'ie 'die"bloeks thus being formed on an angle with relation to the i'ron tface or theftap body; gives the'proper angular setting to the cir-L cular chasers and' controls thelproperci-itting edgeand clearance thereof.

Each of the chasers or cutters i5 is sabstan- 'tially circular but; with asegmental or sectional part1 thereof removed and has substantially,"

straight parallel grooves l4 cutt here in insteadof spiral threads These grooves terminate in a depthwise cutting edge l 6 Each circular. chaser isrturned and ground on a slight taperonfthe'outside diameter to allo'wthe I proper clearance and guide for the Echaser angle,

the diameter 'at the fron't being less than'that at the rear of the chaser with theresult that the front portion of the'chaser does' the cutting while 7 the rear'portion guidesor pulls the-chaser on to the work with the grooves {acting as a guide -except for chasers used for short tapered fthreads wherfe the full width' 'of the c haser is engaged cutting thethreads. j

on the, chaser block, a proper clearanceand head 3 is provided in the front 1 'videdby six, etc. 7 v V a a l I 1 When milling or grinding the chaser grooves; it is necessary that the circular chaser blank' be By locating he chaser in an angular position lead for the thread is obtained and by usingthis angular location of the chaser, the chasers can'be ground independently andv not in sets of fouror 1 t more which would be necessary were the chasers' provided with spiral grooves In other words, if

the chasers were provided with spiral grooves,

this would require that the entireset of Chasers be ground on the cutting edge exactly tlre'same to secure the proper cutting position and it is p practically impossible for any operator to adjust them correctly.

All of the chasers of a set. are formed exactly "thesame but the heighth from the rear iaceat the point of the cutting edge will vary so that, in

manufacturing 'these 'chasers, all of the chasers; are in'acliined exactly'the same until the last operation when the back'faces of the chasers are ground to suit the position of the cutting edge and, consequently, the position of the circular chaser'end-wise will always remain -the same with relation to the top point of thethread. This is a very important point for, without this, the

fersfof all of the chase'rsof the set are ground-off exactly alikefso that the chaser-Swill alls'tart t cut at thesame time.

The grinding of 'the'back face or the c aser m relation to the circular grooves'de'pends upon'the' structure would be too 'complicated for the aver 7 age opera-tor toset and impracticalfor general use. After this grinding the topiaces and cham number o'f chasers'used in' theta'p. For instance; if four chas'ers are used, the distance between the groundback iface of jthe chaser to the center ortheg-roove varies'one-fourth of the distance between the grooves. Wheresix-chasers are -used,

the distance betwee'n'th'e grooves or-pitch is ditipped ata predetermined angle equal to the same. angle that'it is tipped'on the chaser block' when mounted in place. This angle on the top face of theblock is governed by the helix angle of the thread onthe work being cut.

The lower diameter at the bottom of the chaser is greater than the diameter at thetop o-r coune ter-bored section. This difference in; diameter of the chaser is predetermined according to'the pitch of the thread to be 'cutaand'the diameter of the work being threaded in order to-keep the diameter o'f'the circular chaseras large as-pose sible.

Thereforaf-to obtain theproper position. I V

of the Chasers, each chaser'is grou nd during the f last operation" onits ba'ek face to 'suitthe par- 'ti'cular pos'i'ti'onfof the cutting edge in the 'tap' body,-a little mo'reb'eing ground o'if-the back of one chaser than off. the back "of -'another,'-see Figs. 10 to 13. l'hi's- -grinding, howe'ver, 'is'in a perfectly 'straightfldirection 1011f plane and 'does notgive' the angularity of the' chaser'relativeto the tap body as this-is obtained by thefangu'larity of the front fac or the chaser'blocks," but it does give the *difiererit positions of the chasers, as shown in Figs. 10 to 13, wherei'nit will be noted that, in Fig. 10, 'thedistance between the lines l2 is less than it 'is between the lines 3-4 in Fi 13, the letters 5A and -B' Showing how the grind-m gradually of the set.

' The front 'faceg-of feachfehaser block is provaries in the. several chasers vided centrally thereof witha forwardly extend ing, exteriorly ground ring orjannularifiange or I pilot I8 for the reception'of a;="similarlyf formed' interiorly -ground surface "I 9 located lon the outer o rear side'iof the serrations 2'0 of the chaser 1-5.

These two ground surfaces form means for properly positioning and supporting the chaser on the block and this pilot is ground closely to fit within the chaser and is provided with a circular serrated opening 2| for the reception of a stepped serrated bushing 22 having a set of serrations thereon, for instance, th of an inch apart as at 23. This bushing also has an integral part of larger diameter in front thereof having serrations thereon, for instance, is of an inch apart as 24. The chaser [5 has its back face provided with a serrated circular opening 25 corresponding tothe serrations of the larger bushing and these several parts, the chaser, the detachable and rotatable two-section bushing and the chaser block are secured together by a screw or bolt 26 having a counter-bored front end for the reception of a suitable tool to release the chaser from its block, the screw being left-handed whereby the cutting of the chaser will tighten the screw. By means of this or a similar combination of serrations, not only is the setting and grinding of the chaser facilitated but the turning of the chaser on its block is prevented. The front face of the bushing is suitably graduated to facilitate the setting of the parts.

It will be understood, of course, that as each chaser is successively ground, it is moved around the serrations to bring the cutting edge thereof to the proper point. Thus, the serrated bushing acts as a means on which the circular chaser is mounted on the one-piece chaser block and insures that the cutting edge of the chaser be set in the proper position for cutting.

Each chaser is preferably counter-bored at its front end, as 21, forming a flanged chamber 21' and this not only provides a chip clearance when the chaser is cutting but permits the proper grinding of the chaser so that it will cut properly. The cut-away or removed segmental portion l5 along the length of the chaser forms a cutting edge with which the counter-bored front end intersects while the serrated opening in the back of the chaser is of less diameter than the counter-bored opening and does not intersect the cutting edge.

From the foregoing, it will be seen that if a bushing were used having only one set of serrations, for instance, 3% of an inch apart, which would be necessary in order that they not be too fine to support the chaser, and the circumference were one inch, then the chaser would have to have its cutting edge ground off 2 of its circumference each time it was ground, but by having a bushing of two diameters with different circumferentially spaced or graduated serrations, the result is that if, for instance, the number of serrations on the smaller bushing is less or approximately onehalf of the number of serrations on thelarger bushing, the chaser can be ground 01f A of an inch each time instead of is of its circumference.

In setting the chaser to a new position, the bushing is moved clock-wise one serration in the chaser block. The chaser is then set back anticlockwise one serration. Now, if the smaller bushing has thirty serrations and the larger has forty serrations, this eliminates a full serration movement. In other words, there is a ratio of practically four to one.

To illustrate this, consider a 4;" pipe chaser for a tap die. 1 equals the diameter of the chaser which is 3.1416 in circumference. 3.1416 divided by thirty equals .1047 which is the movement when only moving the bushing clockwise in the chaser block and 3.1416 divided by fortyequals .0785 which is the back movement when moving the chaser anti-clockwise on the bushing. Thus, we have moved the thirty serration circumference ahead one complete serration but have moved the chaser on the bushing back in proportion or in ratio of thirty to forty. Therefore, subtracting .0785 from .1047, the remainder is .0262, which is the amount left to grind off the face for the new setting. Thus, the amount to be ground off the circular chaser is in proportion as thirty is to forty.

It will thus be seen that I have provided an improved tap having circular chasers of improved form and construction together with improved means for supporting them, which supporting means includes means for predetermining the exact amount to be ground off the chaser at each grinding thereof while insuring not only long life to the chaser but an accurate settingof the chaser to correspond with such grinding.

Among the numerous advantages of this improved circular chaser is not only the longer life thereof as compared with the ordinary form of chaser because there are quite a few inches of periphery provided for grinding, but the chaser grooves can be readily circularly ground, the cutting edge is protected when the die is collapsed as the cutting edge is rolled away from the chip instead of dragging through and the heat is carried away from the cutting edge rapidly due to the large cross section of the chaser. The chaser can be readily made in a screw machine and has a natural clearance similar to a milled chaser. No backing off is required. The cutting edge can be readily sharpened and the chaser can be readily taken out and returned, and there is a reduction in the stock or number of chasers required to be carried on hand. Furthermore, the chasers can be used for right and left hand threads. by simply changing the angle of the chaser block slide opposite to that for right hand thread cutting. It will be understood, of course, that the coarseness of the grooves of the circular chaser can be varied as may be desired.

The core piece 2 is provided with a series of circumferentially formed cam surfaces 28 corresponding with the number of chaser blocks and co-operating with the circumferentially formed cam surfaces H on the inner ends of the blocks (see Fig. 5). These cam surfaces somewhat resemble teeth or flutes and they taper longitudinally of the core piece, having the same taper that the threaded piece or pipe coupling is to have.

Therefore, when various tapers are to be threaded on the work, the core pieces are changedfor that purpose and are, therefore, interchangeable.

The tap body I is located within a suitable sectional housing made up of a series of rings or annular members and, therefore, mounted on the body is a ring 30 carrying a handle 3| by means of which this ring may be turned to set the chasers. In this ring 30 are two elongated slots 32 and in these slots are two stud screws 33 for securing the ring 30 to a ring 35 to prevent independent longitudinal movement while permitting rotative movement of the ring 30. The ring 30 is provided with two roller studs, the rollers,

i moves with the ring 42 and thusv causes the core piece :2ito move forward or backward with the Vio "rings, dependingl'on which way ?the, .-ringis In the corezpiece '2 there is aiafitted-hole 38 for the "reception of a crosspin and this pin extends "through an elongated slot 40 in the body I and into a fitted hole in a ring 42. This elongated slot 40 thus permits themovement. of the rings just described 5011 the ,tap body When the rings move .forwardor backward-on the shifting "of the handle" 3;], this cross pin 39 turned. When" the tap :isiset to start ithneadirig,

the housing is in position so that-a :t'rip ring :43 contacts with the end of.- ;the coupling C to be threaded and the chasers do: not quite contact with the Ebevel'of the coupling. Thus, a's the'itap isabrought to the chuplinggthe tap body I;, togetherr with its chaserfblocks and chaserszrare fedinto-lthejwork and the ring-43' contacts with the face-of thecoupling C, stoppingthe forward travel .of fthe'rhous'ing rings with the body VI of V thetapand when so stopped, this, offcourse, stops 'theforward travel of thering 42 together with heminwilliand the core'piece 2;-

-As the ta pbody-glfand its chasers 15 enter the, work, the ichas'er blocks are bearing'on the large l end-of the tapered core piece ,2 since the slots '40 in thepbodyjl permit thegfront end ofjthe core piece to mrojectsufficiently beyond the chasers for this purposenwhen' the chasers are set-by the handle 3rl, and as the tap body 1 feeds intothe work, the chaser blocks slide forwardly along the tapered core piece,j-held against longitudinal movement, toward the {small end-thereof. In the" present improvement, by reason of the fact that the chaser blocks slide forwarfdly'along thetapered core piece and the-'core held'against movement duringthe cutting or;threading of the work, the length-of 'thethread in ,a piece of-"work is--con-. trolled by the exact; length of the taper on the core piece so that the taper on the work is an exact-copy of the taper on the core whereas, if

ft he core ,piece moved relative to the cutters,*the

taper on the corecould not be anVeXa ct .copy of the taper lcnflth'e work because thetaper on the 7 core would have to be longer :and, being longer, :wouldgtherefore, have tobe less than the taper I 'on the work. There are; many disadvantagesin I providing a=core-piece that rnovesrelativeto the cutters during the, threading operation for,among other things, this would require complicated :spondsf-exactly with :thelength of' the taper on the work, thus doing .away with an increased 7 length of -cor'e and,consequently,bomplicatedmechanism-to operate that;- core. 1

The thread iscompleted when-theangle or in- 'clinedcam faces -l3 on theends ofithe circular V chaser blocksreach the angle 44 at the endof the core piece 2 so that when the tap body 'I and its chasers l5 are moved further forward, these angles allow the-chasers and blocks to :collapse "out-of the thread. 7 .The tap can then be moved out of the couplingand the chasers reset by the handle :3] tor-the next" threading.

The adjustment for-diameter or size of coupling is obtained by two adjusting screws 45, seeFi'g.

' of these parts.

In the-ring 35 there are a pair of blocks 46, each secured to the ring 35 by two screws 41. On a stud of each block ;46 is arroller 48 and these rollers slide in elongated slots 490i the body ,I, holding the ring 35 in place radially but allow.- ing it to slide l0ngitudinally."

,The ring 42 is "attached to the ring 35 b-yrtwo' stud screws 50 which pass through elongated I slots in the ring 35 and this ring 35 carries the two adjusting screws hereinbefore referred to. When one is loosened andthe other tightened, it causes the :stud screws to move in the elongated, slots -0f the ring '35 and as they are ,tight in :the ring 42; this causes the'ring 42 to turn' V relativeto the tap body :I and when the position of this ring 42 is changed, the cross pi'n 39 moves.

with .it and, as the pin islfi tted intothe core= piece, the core piece also turns, thus circularly adjusting the cam surfaces 28 of thecorepiec'e and thereby "adjusting the chaser slide blocks 5 and 'chasers 15 to regulate their position for cutting-larger orsmaller diameters of threads.

' Forthe purposeof regulating the'length of the screwing :it into or out of the housing ring .5l clamped over a'flangeof the adjusting ring" 42.

thread-to-be cut, the trip' ring 43 is adjustable by T In this improved structure, the tap body I revolves when-the trip ring ,43 contacts with the work. At this time, the ring '43 stops rotating together with the housing ring 5| which bears against thebearings of .a platel52 located between 30, '35 and 42 rotating together by reason of the The plate-52 is ,providedwith a series of balls5l which engage the ringsffi lj and42, 7 r 1 When using this tapon a vertical spindle machine the weight of the core piece and] associated parts must be compensated for. Otherwise, they would remain down and thetap might be reset before being moved out of the'coupling. Therefore,- a spring 52'! or other. counterbalancing frollers 48Lextending into .thelslots- 49 of the body;

means may .beutilized for holdinglup; the weight its tether end suitably supported and-will holdup approximately two-thirds of the weight, the

chaser blocks whenin collapsed position also as "sistingcin holding the Weight of theparts since theinclined ends I 3 of the. blocks willoverlap the a inclined 12116144101? the fcorpiece, j c

,practice, a floating adapterjis used to'propk thespindle of thelmac'hinelfor rotating thetap utilized to form thecadapter. {a c ,In engagement with these flanged surfaces and betweenthe .same is aplate 55 and these three parts, ,the tap body flange,.the shank flange and the intermediate'plate '55,:are secured together by three. shoulder s'crews56 so as to permit a certain amount of side play. The plate 55 is provided withapair of elongatedlslots '180 degrees apart tap body. 7

Carried by-the shank flange seat Q metYJde-Q V In practice' one end of this spring V is attached to the inner end of the core piece with r andcin'to these slots 55 extend rollers carried by two screws 56' projecting frorn'the flange of the grees ap'art ,are two 7 screws also provided "with rollers extending into two elongated slots in the fi plate;55. a V;

1. The shankflange 53 does not float' but the above jthe rings ;5| and-42, and all mounted on a sleeve 5Z'-carried by the-bodyjLthe tapbody and rings in c erlyalign the-ltap with the center of the'coupling to be threaded and maintainit'there while the l 1, spindle wofthe machineis rotating the tapg Forh rQ this purpose, the ,fiange 53 of thelshank, that its v is, together "withja flan e -5410f the tap body I, 6'0

Cir

arrangement permits the tap to move or turn circumferentially relative to the plate 55 by means of certain of the elongated slots in one direction and the plate and tap to move or turn circumferentially together relative to the shank 53 by other elongated slots in an opposite direction, thus giving a floating connection to the tap at all times.

It is to be understood that, by describing in detail herein any particular form, structure or arrangement, it is not intended to limit the invention beyond the terms of the several claims or the requirements of the prior art.

Having thus explained the nature of my said invention and described a Way of constructing and using the same, although without attempting to set forth all of the forms in which it may be made, or all of the modes of its use, I claim:

1. A collapsible tap comprising a body, a series of circularly formed radially shiftable chasers, radially sliding blocks carried by the body and supporting the chasers, said blocks having cam formed faces at their inner opposed ends, a core piece located centrally of the body and having cam faces co-operating with the cam faces of the blocks, and means for rotating the core piece thereby to radially adjust the blocks and chasers, the cam faces of the core piece having a tapered formation in the axial direction of the core piece whereby, on the relative movement of the core piece and body, the chasers will be radially shifted to cut a tapered thread, said blocks having an angular inner end and said core piece having an angular end co-operating with the angular end of the blocks for permitting the collapse of the chasers, and means for collapsing the chasers.

2. A collapsible and receding tap comprising a. sectionally formed housing comprising a series of annular members, a body located therein, said body and housing having a relative movement, a core located centrally of the body, said body and core having relative longitudinal movement and circular movement, means connecting the core with the housing, means for shifting the housing relative to the body thereby to shift the core relative to said body, means for rotating the core relative to the body, said core being of interchangeable form, a series of radially shiftable slides, an interchangeable nose for supporting said slides on the body, and a series of circularly formed cutters carried by the slides and located angularly with relation thereto, said slides and core having co-operating cam faces at *the inner ends of the slides and extending circularly of the core and tapered lengthwise thereof whereby the slides and cutters will be adjusted radially and also shifted radially to cut a tapered thread, the relative longitudinal movement of the core and body automatically shifting the cutters radially to cut such tapered thread.

3. A collapsible and receding tap comprising a sectionally formed housing comprising a series of annular members, a body located therein, said body and housing having a relative movement, a core located centrally of the body, said body and core having relative longitudinal movement and circular movement, means connecting the core with the housing, means for shifting the housing relative'to the body thereby to shift the core relative to said body, means for rotating the core relative to the body, said core being of interchangeable form, a series of radially shiftable slides, an interchangeable nose for supporting said slides on the body, a series of circularly formed cutters carried by the slides and located angularly with relation thereto, said slides and core having co-operating cam faces at the inner ends of the slides and extending circularly of the core and tapered lengthwise thereof whereby the slides and cutters will be adjusted radially and also shifted radially to cut a tapered thread, the relative longitudinal movement of the core and body automatically shifting the cutters radially to out such tapered thread, and means for counterbalancing the core when the tap is used in a vertical position.

4. A collapsible automatically operative tap comprising means acting automatically and independently of any supervisory act on the part of an attendant, periodically or at regular recurring intervals, gradually to retract the cutter and then collapse the same and a body, a series of radially shiftable sliding blocks carried thereby, a series of circularly formed chasers carried by said blocks, said blocks and chasers having co-operating means for positioning the chasers relative to the blocks, and means located axially of the body and co-operating with the inner ends of the blocks for radially adjusting the blocks and for radially shifting them relative to the work, said means being stationary during the threading of the work while the cutters move therealong to thread the work, the said stationary means being in the same longitudinal position with relation to the work from the beginning to the end of the threading operation.

5. A collapsible automatically operative tap comprising means acting automatically and independently of any supervisory act on the part of an attendant, periodically or at regular recurring intervals, gradually to retract the cutter and then collapse the same and a body, a series of radially shiftablecutters carried thereby, radially sliding blocks carried by the body for supporting the cutters, and means in operative engagement with the inner ends: of the blocks for adjusting the cutters radially of the body, said means being stationary while the cutters move therealong to thread the Work and co-operating with said cutters for automatically shifting them radially to cut a tapered thread, the said stationary means being in the same longitudinal position with relation to the Work from the beginning to the end of the threading operation.

6. A collapsible automatically operative tap comprising means acting automatically and independently of any supervisory-act on the part of an attendant, periodically or at regular recurring intervals, gradually to retract the cutter and then collapse the same and a body, a

' series of circularly formed radially shiftable cutters carried thereby, radially sliding blocks carried by the body for supporting the cutters, and means in operative engagement with the inner ends of the blocks for adjusting the cutters radially of the body, said means being stationary while the cutters move therealong to thread the work and co-operating with said cutters for automatically shifting them radially to cut a tapered thread, the said stationary means being in the same longitudinal position with relation to the work from the beginning to the end of the threading operation.

'7. A collapsible automatically operative tap comprising means acting automatically and independently of any supervisory act on the part of an attendant, periodically or at regular recur- V 'of an attendant,1periodically-orl at regular recurring interval sijgradually, to retract the cutter I :and th'en collapse the same and a body, a series of circularly formed radially shiftable cutters carried thereby, and axiallylocated means, said means being stationary while the cutters move therealong to thread the work and co-operating with said cutters to effect the automaticshift ing: thereof radiallyinwardly during the thread:-

. ing .opcration to cut a, tapered thread and having means for efiectin'g the collapsing of' the cutters inwardly on the completion of the cutting operation and also having means for adjusting the cuttersradially of thebody to set the cutters,

' the said stationary means being in the same longitudinal positionwith relation to the work from a the beginningto theend of the threading operation. 7.:

V 8. A collapsible automatically operative tap comprising means actingautom atically and independently of anysupervisory act on the part ring intervals, graduallyito retract the cutter and then collapse the same and a body, a series of I 'icircularly formed radially shiftable cutters care 7 means being stationary while the cutters move therealong to; thread the work andco-operating ried thereby,. and'axiallylocated means, said with said cutters to effectthe automatic shifting thereof radially inwardly during the threaclingoperation to cut a tapered thread and' ha ving means for cffectingithe .collapsingof'the cutters finwardly onthe comp'l'etiongof the cutting operation, said axially located means comprising a' V core tapered inthe direction of its length and conforming to the'taper to be imparted to the work whereby thetaper on the work will correspond to the exact taper on thej'core, the said stationary meansbeing in the same longitudinal position withvrelation to the work from the beginning to the .end of the threading operation.

9. A collapsibletap comprising a, body, a series of radially sliding blocks carried thereby,

circular chasers carried by the blocksand angularly located relative thereto and each having its back face 'groundjofiin a straight direction or plane, one to a greater extent than the preceding chaser, and an axially located corepiece, said core piece being stationary while the chasers move therealong to thread the work, and having acircular series of cam -facestapered in the die rection of the length of the 'corean'd correspondinginnumbervvith the number of the'ch'asers and co-operatingwithsaid cutters to effect the automatic shifting thereof radially inwardly during the threadingoperation to cut a tapered a core piece locatedcentrally of the body'and 7 having cam faces corresponding in number with;

thread and also having ineans'ior effecting the collapse of thecutters onfthe completion of the cutting operation, means for rotating the core piece thereby radially to adjust the cutters, and a [work engaging structure freely rotatable relative to the body during the thread cutting operation.

;10. A collapsible tap comprising a body, a se- 7 1 ries of circularly formedLradiallyishiftableicubV ,ters, radially'sliding blocks carried by the body 7 for supporting'the chasers,v said blocks having cam formed faces at their inner opposed ends, and

' the number of'cuttersrand having a tapered formation in the direction of the length of the jcorepand said core ,piecebeing stationary while the cutters move therealong to thread the work ,and co-operating with saidblocks to effect the automatic shifting ofethe cutters Iradially inwardly during' the cutting operation to cut a ta- -'pered thread, saidf c'ore piece havihg' meansfor effecting the collapsing of the cutters inwardlyon Q a the completion of the cutting operation, said bodyand core piece having a relative longitudinal movement and V a relative circular movementi 'whereby, during the relative circularmoveme'nt,

the cutters will be radially adjusted and during the relative longitudinal movement thecutters willbe automaticallyshiftedradially .1'1.A collapsible tap comprising a body, a core memberlocated centrally of the body, said body having a longitudinal"movement relative to the coreduring the cutting of a thread and said core having a longitudinal movement relative to the 1 body to set the'chasers saidcore and bojdyalso having a relative rotational movement, a series of radially shiftable chasers'carried by'the body and co-bperating with'the core whereby during the relative rotationalmovement, the cutters will I be radially adjustedi and, during the longitudinal movement of the vbody relative to the core, the

cutters will be automatically j'radially shiftable inwardly-to cut a tapered thread, and a- Work,

body during the thread cutting operation.

12. Acollapsible tap com'prising'a body, a circularly formed housing therefor, said body and l housing having a relative longitudinal movement,,a seriesof chasers, and a series of radially slidable blocks carried by the body for support- 7 ing the chasers thereon, said blocks and core have i ing co-operating meanswhereby, on the longi tudinal movement of the body relative to the tocut a tapered thread and on the relative rotational movement of 'the body and core, thechasers will be radially adjusted.

13. In an automatically operative tool for 1 forming taper threadsnthe{combination of a tool body; means, comprising ,a cutter movably 'mounted onthe body, for cutting a thread when the tool body and'th e workto bethreaded are riodically' or at'regular recurring intervals," by

relative axial movement of the said body and the a 'work gradually to retract .thecutter relative "to the work during the, thread-cutting; operation, said means comprising a slide mounted for movement on the body parallel to the axis thereof and a work engaging structure freely rotatable on the slide duringthe thread-cutting operation.

forming taper threadsthe combinationof a tool body; means, comprising a cutter movably V mounted on the body, for cutting a thread when :engaging structure freely rotatable relative to the core the chasers will be radially shifted inwardly t given relative rotational and axial movements; g and means movablysupportedon the tool body f and automatically operableindependentlyof any' supervisory act onthe part of anattendant, pe-

14. In an automatically operative tool for' the tool body and the work to be threadedare given relative rotational and axial movements;-

and means movably supported on the' tool body and automatically operable independently ofanysupervisory act on the part of an attendant, pee

riodically or at regular recurring intervalsiby relative axial movement of the saidbody and the work gradually to retract the ..cutter relativeto the work during the thread-cutting operation,

said means comprising a slide mounted for movement on the body parallel to the axis thereof, a structure freely rotatable on the slide during the thread-cutting operation and comprising a workengaging member adjustable axially of the tool body.

15. A collapsible automatically operative tap comprising means acting automatically and independently of any supervisory act on the part of an attendant, periodically or at regular recurring intervals, gradually to retract the cutter and then collapse the same and a body, a series of circularly formed radially shiftable cutters carried thereby, axially located means stationary during the movement of the cutters 'therealong during the cutting of the work and co-operating with said cutters to effect the automatic shifting thereof radially inwardly during the threading operation to cut a tapered thread and having means for effecting the collapsing of the cutters inwardly on the completion of the cutting operation, and a work engaging structure freely rotatable relative to the body during the thread cutting operation.

16. In an automatically operative tool for forming taper threads, the combination of a tool body, means comprising a cutter movably mounted on the body for cutting a thread when the tool body and the work to be threaded are given relative rotational and axial movements, and means movably supported on the tool body and automatically 10 comprising a slide mounted for movement in the body parallel to the axis thereof, and a work engaging structure freely rotatable relative to the body. V

' WILLIAM J. HOGG1 

